Also, your min_size is set to 2. What this means is that you need at least 2 copies of your data up to be able to access it. You do not want to have min_size of 1. If you had min_size of 1 and you only have 1 copy of your data receiving writes and then that copy goes down as well... What is to stop one of the other 2 copies coming up before the copy that was last up except not knowing about the current state of the data. Now you're in a state where your data is corrupt in that the client doesn't know what state the data is in.
On Fri, Jun 2, 2017 at 10:34 AM Ashley Merrick <ashley@xxxxxxxxxxxxxx> wrote:
_______________________________________________You only have 3 osd's hence with one down you only have 2 left for replication of 3 objects.
No spare OSD to place the 3rd object on, if you was to add a 4th node the issue would be removed.
,AshleyHello,I am playing around with ceph (ceph version 10.2.7 (50e863e0f4bc8f4b9e31156de690d765af245185)) on Debian Jessie and I build a test setup:
$ ceph osd treeID WEIGHT TYPE NAME UP/DOWN REWEIGHT PRIMARY-AFFINITY-1 0.01497 root default-2 0.00499 host af-staging-ceph010 0.00499 osd.0 up 1.00000 1.00000-3 0.00499 host af-staging-ceph021 0.00499 osd.1 up 1.00000 1.00000-4 0.00499 host af-staging-ceph032 0.00499 osd.2 up 1.00000 1.00000
So I have 3 osd on 3 servers.I also created 2 pools:
ceph osd dump | grep 'replicated size'pool 1 'cephfs_data' replicated size 3 min_size 2 crush_ruleset 0 object_hash rjenkins pg_num 32 pgp_num 32 last_change 33 flags hashpspool crash_replay_interval 45 stripe_width 0pool 2 'cephfs_metadata' replicated size 3 min_size 2 crush_ruleset 0 object_hash rjenkins pg_num 32 pgp_num 32 last_change 31 flags hashpspool stripe_width 0
Now I am testing failover and kill one of servers:ceph osd treeID WEIGHT TYPE NAME UP/DOWN REWEIGHT PRIMARY-AFFINITY-1 0.01497 root default-2 0.00499 host af-staging-ceph010 0.00499 osd.0 up 1.00000 1.00000-3 0.00499 host af-staging-ceph021 0.00499 osd.1 down 1.00000 1.00000-4 0.00499 host af-staging-ceph032 0.00499 osd.2 up 1.00000 1.00000
And now it stuck in the recovery state:ceph -scluster 6b5ff07a-7232-4840-b486-6b7906248de7health HEALTH_WARN64 pgs degraded18 pgs stuck unclean64 pgs undersizedrecovery 21/63 objects degraded (33.333%)1/3 in osds are down1 mons down, quorum 0,2 af-staging-ceph01,af-staging-ceph03monmap e1: 3 mons at {af-staging-ceph01=10.36.0.121:6789/0,af-staging-ceph02=10.36.0.122:6789/0,af-staging-ceph03=10.36.0.123:6789/0}election epoch 38, quorum 0,2 af-staging-ceph01,af-staging-ceph03fsmap e29: 1/1/1 up {0=af-staging-ceph03.crm.ig.local=up:active}, 2 up:standbyosdmap e78: 3 osds: 2 up, 3 in; 64 remapped pgsflags sortbitwise,require_jewel_osdspgmap v334: 64 pgs, 2 pools, 47129 bytes data, 21 objects122 MB used, 15204 MB / 15326 MB avail21/63 objects degraded (33.333%)64 active+undersized+degraded
And if I kill one more node I lose access to mounted file system on client.Normally I would expect replica-factor to be respected and ceph should create the missing copies of degraded pg.
I was trying to rebuild the crush map and it looks like this, but this did not help:rule replicated_ruleset {ruleset 0type replicatedmin_size 1max_size 10step take defaultstep chooseleaf firstn 0 type osdstep emit}
# end crush map
Would very appreciate help,Thank you very much in advance,Oleg.
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